[OpenMP] Fix potential division by 0

[Nawrin]

Summary

This patch fixes potential division by 0 in case hwloc does not recognize cores (or architecture has no cores).

Patch by Andrey Churbanov

[jdoerfert]

LGTM

openmp/runtime/src/kmp_affinity.cpp

if (!KMP_AFFINITY_CAPABLE()) {
     else
       nCoresPerPkg = 1; // no PACKAGE found
     o = hwloc_get_obj_by_type(tp, HWLOC_OBJ_CORE, 0);
     if (o != NULL)
       __kmp_nThreadsPerCore = __kmp_hwloc_get_nobjs_under_obj(o, HWLOC_OBJ_PU);
     else
       __kmp_nThreadsPerCore = 1; // no CORE found
     __kmp_ncores = __kmp_xproc / __kmp_nThreadsPerCore;
+    if (nCoresPerPkg == 0)
+      nCoresPerPkg = 1; // to prevent possible division by 0
     nPackages = (__kmp_xproc + nCoresPerPkg - 1) / nCoresPerPkg;
     if (__kmp_affinity_verbose) {
       KMP_INFORM(AffNotCapableUseLocCpuidL11, "KMP_AFFINITY");
       KMP_INFORM(AvailableOSProc, "KMP_AFFINITY", __kmp_avail_proc);
       if (__kmp_affinity_uniform_topology()) {
         KMP_INFORM(Uniform, "KMP_AFFINITY");
       } else {
         KMP_INFORM(NonUniform, "KMP_AFFINITY");